Within the past decade, it has emerged that cells package various molecules into tiny bubble-like parcels called extracellular vesicles to send important messages – in sickness and health. The potential for using these vesicles in diagnosis and treatment is now under intense investigation.
Extracellular vesicles (EVs) are so small they can only be seen through high-tech electron microscopes. The membrane-covered structures are roughly in the same size range as viruses, bacteria and platelets.
For decades, scientists thought the cargo of EVs – which can consist of various molecules such as proteins and genetic material – was just debris.
More recently, they have begun to understand the importance of EVs in health and disease and how they might be used to ferry drugs to their targets.
However, there are still many large gaps in our understanding of EVs.
For example, because EVs are found in bodily fluids like blood, urine and cerebrospinal fluid, researchers are finding it nearly impossible to determine where they come from, how they are made or how they release their cargo of molecules.
Another mystery is why the same EV cargo can result in different outcomes.
Now, a new study – led by Rutgers University in Piscataway, NJ, and published in the journal Current Biology – offers some new clues about EVs.
Lead author Maureen Barr, a professor of genetics at Rutger’s, says EVs are both exciting and scary because we do not know the mechanisms that control what goes into them. She explains:
“It’s like getting a letter in the mail and you don’t know whether it’s a letter saying that you won the lottery or a letter containing anthrax.”
Prof. Barr says the more we find out about how a cell makes and packages proteins, lipids and bits of genetic material into EVs, the more we can use that knowledge to develop drugs and therapies to treat diseases. For example, one use could be to prevent cancer cells from using EVs to send messages that promote tumor growth.
For their study, the team investigated EVs in Caenorhabditis Elegans. The roundworm is a very useful model for understanding human biology at the level of cells – for example, many of its genes are similar to ours.
The researchers identified 355 genes that offer significant information about the biology of EVs and the role they might play in human diseases.
One in ten of the genes appear to control the formation, release and possible function of the vesicles.
The study also identifies new pathways that might control how cells produce EVs and choose their cargo, including proteins responsible for the most commonly inherited disease in humans – polycystic kidney disease.
Prof. Barr says cells secrete polycystic kidney disease gene proteins in EVs in both humans and worms, and no one knows why. She concludes:
“When we know exactly how they work, scientists will be able to use EVs for our advantage. This means that pathological EVs that cause disease could be blocked and therapeutic EVs that can help heal can be designed to carry beneficial cargo.”
Meanwhile, from another recently published study of roundworms, Medical News Today learned that a Velcro-like molecule essential for sperm to be able to attach to eggs during fertilization is the same as one discovered in humans 10 years ago. The researchers suggest the finding could lead to better fertility treatments and contraceptives.